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Contrasting Response of Ultrafine Particle Number and PM 2.5 Mass Concentrations to Clean Air Action in China
Author(s) -
Zhao S. P.,
Yu Y.,
Yin D. Y.,
Qin D. H.
Publication year - 2021
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2021gl093886
Subject(s) - ultrafine particle , aerosol , atmospheric sciences , nucleation , particle number , noon , aerodynamic diameter , particulates , environmental science , particle (ecology) , mass concentration (chemistry) , mode (computer interface) , materials science , meteorology , chemistry , physics , nanotechnology , thermodynamics , geology , oceanography , organic chemistry , volume (thermodynamics) , computer science , operating system
The strictest ever Clean Air Action has been implemented since 2013 at nationwide scale in China. Nevertheless, PM 2.5 (particulate matter with aerodynamic diameter smaller than 2.5 μm) mass and number of ultrafine particles (UFPs, the particles with diameters smaller than 100 nm) exhibited contrasting response to the emission mitigation policies. Unlike reduction of PM 2.5 and number of accumulation mode particles, UFPs number decreased from 2012 to 2015, and then has begun to increase sharply since 2016, and annual change of number in nucleation mode particles can reach 40% at noontime during 2017–2019. We examined inter‐annual trends of mode diameter, frequency of new particle formation (NPF) events, formation and growth rates, and particles were found to be much finer and NPF events have been more frequent since 2017. The much higher temperature and stronger solar radiation induced by PM 2.5 reduction could promote the formation of secondary aerosol particles at noon.